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Re: Solid-state TC - transformer design

Tesla List wrote:
> 
> >From 100624.504-at-CompuServe.COMTue Oct 29 22:38:48 1996
> Date: 29 Oct 96 07:11:40 EST
> From: Alan Sharp <100624.504-at-CompuServe.COM>
> To: Tesla List <tesla-at-poodle.pupman-dot-com>
> Subject: Re: Solid-state TC - transformer design
> 
> >   Has anyone tried using a counterpoise ground instead of grounding the
> >opposite side of the output transformer(the end not connected the base
> >of the secondary) to earth ground? I have Duane A. Bylunds book and
> >there is a section on counterpoise grounds.
> >   I would like to use this method instead so I can operate the coil
> >indoors. His book leaves a few questions unanswered. Like can the
> >opposite side of the output transformer be connected to ONLY the
> >counterpoise?
> 
> No
> 
> The counterpoise will reduce the currents in the earth wire by up to
> 50% according to Duane. But if you have no connection to earth ground
> then your counter poise / coil system will be at an extremely high
> voltage compared to the electronics - like 200 kV accross the output
> transformer - ZAP!  The counterpoise is floating but it is still connnected
> by capacitance to ground.
> If you then connect the electronics also to the counterpoise
> the voltages will then appear accross the mains transformer - ZAP :)
> 
> I've got away with using the electrical ground but then I've lots of earthed
> metal pipes going underground.
> 
> Ground connection is essential but a counterpoise will reduce the ground
> currents. A pair of electronic magnifiers driven out of phase would also
> significantly reduce the earth currents.
> 
> The only system that I can see possibly working without a ground
> connection is the "Oudin" type coil. A long horizontal seconday coil with a
> toriod on each end, driven by a conventional primary around the middle.
> Or of course a coil operating inside a large metal box :)
> The best counterpoise suggested for your appartment was of course
> the battleship Missouri but this totally ignored the practical dificulty of
> drillinga hole in steel armour deck plate for the earth connection ;)
> 
> Counterpoises are on a my long to do list of experiments. I missed out
> on picking up some really cheap copper clad board at a recent ham fest.
> I could have etched a fine tree like structure on it - retaining 90% of the
> copper, all electricaly connected but no paths for eddy currents. And
> arranged them in an umberella shape around the coil base.
> 
> Have fun,
> 
> Alan Sharp (UK)


  Thanks for the information! That answers another one of my nagging
questions. I guess I'll have to run a cable to earth ground somewhere!